Hello everyone

Last night I spun my 1989 Z51 out of control. I was coming out of a circle. Gave a little too much gas. The rear wheels broke loose and started to come around.I started to control the front wheels and hit the brakes the car started to recover and then spun 1890 degrees. Finally and safely it stopped.
I am not sure that the ABS system kicked in. Frankly I am not sure I pressed hard enough to engage the ABS. So, I was thinking of a road I know that is very wide and unused. If I bring the car up to a speed say 50 MPH, dry pavement, slam on the brakes will the ABS engage or do I need a wet road. Thank you

PS: Tires are brakes have a bout 15K on them

 

I am not an expert on this but I think you need to brake awful hard to engage ABS on smooth dry concrete in a straight line. I never have. Maybe try gravel. Dan

 

you caused snap over steer by hitting the brakes while the car was upset. Not a smart move.

Would have been better to stay in the gas or at worse gone neutral.

ABS will not do anything in the situation you were in.

 

1890 degree spin thats like 5 times around WOW JUST KIDDING

 

This is correct. When you brake a car, you transfer more of the load to the front tires, which means you also transfer more grip to them and take it away from the rear tires. A car is inherently less stable (tends to oversteer) in this condition, at least until the point where you lock the front tires up completely. It's the same for any car. ABS won't help with that. In fact it could make it worse by keeping you from locking the fronts. Newer cars have some stability control that helps apply braking to either side of the car to keep it from spinning, but no C4 has that.

ETA: This is a good reason why I think everyone should attend some high-performance driving education, and/or autocrosses. Learning car control is still important as long we don't have self-driving cars.

 

Yep, as others have said hitting the brakes when the back end breaks loose and starts to 'come-around' is the worst thing you can do. It took me a few spins on the autocross course to figure that out years back. On the positive side, neither you or the car were hurt and now you know what not to do.

As far as checking the ABS, find a quiet piece of road and slam the brakes ( you don't need to be going all that fast) and see if the ABS kicks in. If you prefer you could find some gravel (you can be going fairly slow) and mash the brakes and the ABS should kick-in.

 

Did it cross your mind your car lacks enough compliance lacking that it is a go kart without the light weight and sticky tires. The other side of the coin is check the rear bushings and worst case add a little rear toe in. Tires are next to look at as far as age inflation tread design and wear rating. Nothing as scary as hard tires with too much tread. They last forever ride nice and like steel on steel for traction.

 

Let's just say he won't do it again!!!

 

Hi

The LSD diff is what makes it so easy for the back to step out, going around a corner with power on causes the diff to spin both wheels equally.
That way you have the inside tire start to spin slightly, doesn't take much to get the other wheel to spin and the back will overtake the front very quickly.

Quite dangerous LSD in the wet with inexperienced drivers, good you found out the bad manners without any damage.
I swear my C4 tries to kill me every chance it gets........ The late C4s got electronic traction control.
We just have to tie a fishing line from left ******** to right big toe for wet weather safety

 

LSD diffs generally promote understeer, not oversteer. And they usually don't cause both wheels to spin equally (i.e. send equal torque to both wheels), but rather send a torque split that depends on the design and setup of the diff (the torque bias). They make it considerably harder to spin the tires with too much throttle, because both tires take a share of the torque. Now what is true is that if you actually apply enough throttle to break both tires loose, you are obviously going get power oversteer. This is super easy to correct, though, by reducing (but not slamming shut) the throttle opening and countersteering. The OP's first mistake was to induce this, and the second was his quick shutting off of the throttle and jumping on the brakes. That's a recipe for oversteer.

 

When I first got my 87, I spun out twice giving it gas in a turn, and this was on a dry pavement. Learned my lesson, I'm very aware of what I'm doing with the car in turns.

 

From my experience cars with IRS, rear of car can suddenly "Snap out" when you're speed cause too much rear body roll. It is part of learning the limitations of your car.
With a solid rear axle I always been able to feel the back of the car get loose before losing control.

 

There's an awful lot of blatantly incorrect info and advice being given in this thread about chassis dynamics and the characteristics of C4s in general. C4s are one of the more forgiving cars in terms of snap oversteer. Unless they are set up in some totally jacked way (and certainly not from the factory), they take a lot of throttle abuse to break the rear loose. The OP's car even has the later suspension geometry, which was even more benign. IRS cars don't inherently have more rear body roll than solid-axle cars. But even if that were true, a car that has a lot of rear body roll will be less likely to spin because it will have less lateral weight transfer at the rear, and more at the front.

 

It has alot to do with the speed and the road. I have dealt with a lot of wrecked IRS cars. Nearly all with rear end and suspension damage. Mostly caused by snap oversteer caused by excessive speed and driver error. Just because it's a z51 doesn't mean you can't over drive the car.

 

post of the year for being grammatically correct..... HOLY ****.... WINNING.

 

Every accident has to do with speed and the road. And you can overdrive any car..of course. Your conclusions about IRS being prone to "snap oversteer" are an overgeneralization. First, most accidents involve at least two vehicles, and the focus on accident causation these days is on driver inattention. Even most single-vehicle accidents don't involve a spin, but they do usually involve some form of IRS. Almost every car built in the modern era has an IRS. Almost all mid-sized SUVs and CUVs do too, and even many full-sized SUVs (Ford and all imports, and the next-gen GMs are going that way too). Do you honestly think these are all prone to snap oversteer, and that most vehicle accidents today are a result of snap oversteer? If IRS was really that dangerous, do you really think every auto maker in the world would have adopted it for everything except their pickups?

Let's rein in all the hyperbole and silliness. C4s have very sound, stable chassis - especially the 1988+ versions. They also have relatively low power. The C4 has been proven to easily and safely handle twice the power of a stock L98. Assuming nothing is broken or massively out of spec, it takes a seriously ham-fisted set of driver inputs to upset one. The problem here was driver error, pure and simple.

 

Hey guys and gals,

I want to thank you for the response. I was just so shocked it broke loose so quick. I think I hit the brakes. I know I steered into the skd and recovered then it went the other way and eventually came around I wish I had a go pro on the dash. One time I over throttled my 69 into a turn. I took my foot off everything and just steered he car. She went right through. This time I was travelling slow on wet pavement. I had just came out of a circle, NJ, and thought I was on the road. I was still on the exit apron of the circle. It was still wet. And the car broke loose. But, thank you all for the input. I actually and area where I can test the ABS. There is an abandoned landing strip near my house. So next wet day I go for a spin, lol.

Thanks again

 

^Do some autocross events. You want to learn what happened? Why it happened? How to drive out of it next time? Go do some autocross events.

You're '69 "went right through" b/c it was doing the same thing....but at a lower speed and lower limit. Lower speed and lower limit made the car more drivable for you, and you controlled it. The 'Vette has higher limits, so when it does slid, the result is going to be "more", and require "more", to fix it.



Boy....this is the truth. Everyone in this thread, outside of MM should enroll in a HPDE or do some autocross....and learn more real facts about cars, handling, suspensions, physics and their car in particular.

The whole point of IRS compared to a solid axle, is better handling. OEM's didn't spend more money on the rear suspension, in order to introduce more "snap oversteer". That is not what has gone on in auto development.


.

 

You are correct. Driver error caused the problem and may have even magnified it. Again thank you all

 

To be clear, my posts aren't a jab at you. Your error has been made a million times by a million people, including me. It's almost always the same one that leads to all the leaving-cars-and-coffee incidents (most of the Mustangs that made this famous are stick axles, btw). I just spent last weekend at the CAM Challenge in Indiana, and the finish to that autocross involved a transition from a right turn into a left turn on the power, with a tight shut-down section afterword (hit a cone there and your run is wasted). I probably saw literally 100 spin-outs just past the finish line as one competitor after another got off the gas and onto the brakes too abruptly. And these were mostly national-caliber drivers. So you aren't at all alone! It's just something to learn from.

And if possible, do some practice in a closed-course environment so that the proper corrections become muscle memory rather than something you have to think about. It's natural instinct to want to slow down when the rear wheels break loose. You have to make yourself overcome the instinctive desire to slam on the brakes when this happens, and the only way to do that is to practice. If you have to think about it, you'll be too late. For better or worse, most new cars now go a long way toward preventing this if the nannies aren't turned off, btw. But it's still a good idea to learn real driving, at least until autonomous cars take over from human drivers.